WORLD INTELLECTUAL PROPERTY ORGANIZATION
International Bureau
PCT
INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
(51) International Patent Classification 6 ;
A23C 1/00, 9/142, 9/18, A23J 1/20
Al
(11) International Publication Number: WO 00/51440
(43) International Publication Date: 8 September 2000 (08.09.00)
(21) International Application Number: PCT/NZ99/00026
(22) International Filing Date: 1 March 1999 (01.03.99)
(71) Applicant: NEW ZEALAND DAIRY BOARD [NZ/NZ]; 25
The Terrace, Wellington (NZ).
(72) Inventors: BLAZEY, Neil, D.; 1252 Morgan Street, Santa
Rosa, CA 95401 (US). KNIGHTS, Ralph, J.; 2327 Hidden
Valley Drive, Santa Rosa, CA 95404 (US). WU, Chao;
4814 Idaho Circle, Aimes, I A 50014 (US).
(74) Agents: CALHOUN, Douglas, C. et al.; A J Park & Son, 6th
floor, Huddart Parker Building, Post Office Square, P.O. Box
949, Wellington 6015 (NZ).
(81) Designated States: AL, AM, AT, AU, AZ, BA, BB, BG, BR,
BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD,
GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP,
KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK,
MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG,
SI, SK, SL, TJ, TM, TR, TT, UA, UG, UZ, VN, YU, ZW,
ARIPO patent (GH, GM, KE, LS, MW, SD, SL, SZ, UG,
ZW), Eurasian patent (AM, AZ, BY, KG, KZ, MD, RU, TJ,
TM), European patent (AT, BE, CH, CY, DE, DK, ES, FI,
FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OAPI patent
(BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE,
SN, TD, TG).
Published
With international search report.
(54) Title: MEMBRANE FILTERED MILK PROTEINS VARYING IN COMPOSITION AND FUNCTIONAL ATTRIBUTES
(57) Abstract
A process is described for treating an approximately neutral fluid milk composition, including milk protein concentrate and milk
plus added whey, by selecting an alkali, adjusting the pH upward, heating, cooling, selecting an acid, and adjusting the pH down before
ultrafiltering and, in a more preferred process, thereafter diafiltering the treated composition. Selection of the appropriate alkali, pH values,
temperatures, acid, and membrane filter porosity results in improved yields of retentate proteins having selected compositions with improved
utility, including a more palatable flavor, a broad range of solution viscosities, an increase in the solubility of the dried retentates in cold water
to nearly 100 %, and an increase in the calcium content of the membrane filtered retentate by about 50 % compared to a similar retentate
from standard milk. Appropriate selection of processing conditions can result in at least one filter permeate with a protein composition
enriched in alpha lactalbumin, a protein that is highly beneficial for human nutrition.
FOR THE PURPOSES OF INFORMATION ONLY
Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.
AL
Albania
ES
Spain
LS
Lesotho
SI
Slovenia
AM
Armenia
FI
Finland
LT
Lithuania
SK
Slovakia
AT
Austria
FR
France
LU
Luxembourg
SN
Senegal
AU
Australia
GA
Gabon
LV
Latvia
sz
Swaziland
AZ
Azerbaijan
GB
United Kingdom
MC
Monaco
TD
Chad
BA
Bosnia and Herzegovina
GE
Georgia
MD
Republic of Moldova
TG
Togo
BB
Barbados
GH
Ghana
MG
Madagascar
TJ
Tajikistan
BE
Belgium
GN
Guinea
MK
The former Yugoslav
TM
Turkmenistan
BF
Burkina Faso
GR
Greece
Republic of Macedonia
TR
Turkey
BG
Bulgaria
HU
Hungary
ML
Mali
TT
Trinidad and Tobago
BJ
Benin
IE
Ireland
MN
Mongolia
UA
Ukraine
BR
Brazil
IL
Israel
MR
Mauritania
UG
Uganda
BY
Belarus
IS
Iceland
MW
Malawi
US
United States of America
CA
Canada
IT
Italy
MX
Mexico
UZ
Uzbekistan
CF
Central African Republic
JP
Japan
NE
Niger
VN
Viet Nam
CG
Congo
KE
Kenya
NL
Netherlands
YU
Yugoslavia
CH
Switzerland
KG
Kyrgyzstan
NO
Norway
ZW
Zimbabwe
CI
Cote d'Tvoire
KP
Democratic People's
NZ
New Zealand
CM
Cameroon
Republic of Korea
PL
Poland
CN
China
KR
Republic of Korea
PT
Portugal
cu
Cuba
KZ
Kazakstan
RO
Romania
cz
Czech Republic
LC
Saint Lucia
RU
Russian Federation
DE
Germany
LI
Liechtenstein
SD
Sudan
DK
Denmark
LK
Sri Lanka
SE
Sweden
EE
Estonia
LR
Liberia
SG
Singapore
WO 00/51440
PC17NZ99/00026
MEMBRANE FILTERED MILK PROTEINS VARYING IN COMPOSITION AND
FUNCTIONAL ATTRIBUTES
5 Technical Field
For the purposes of describing this invention, the background for this invention, and
the examples contained herein, the term "milk" or "fluid milk" means skim milk or nonfat
milk (as described in the U.S. Code of Federal Regulations, 21CFR 131), or concentrated skim
milk prepared by evaporation or membrane filtration processes, or the fluid prepared from
10 reconstituting powdered skim milk in water, or skim milk to which milk solids have been
added for standardization purposes, or skim milk with added whey or whey protein
concentrate. Use of this term "milk" is not meant to limit the invention but is meant as a
general description of milk protein containing fluids that can be advantageously processed by
this invention to produce the products having the beneficial characteristics derived from this
15 invention.
Background Art
The proteins of milk are valued for nutritional and functional properties when used as
ingredients in processed and prepared foods. The proteins are generally categorized into two
classes with one class being a heterogeneous mixture called casein and representing
20 approximately 80% of the proteins found in milk, and the second class being a heterogeneous
mixture called whey proteins comprising the remaining approximately 20% of the proteins in
milk. These proteins are separated from milk using a variety of chemical and physical
processing techniques.
Casein is prepared by adjusting the pH of milk to near the isoelectric pH of casein at
25 which pH the casein precipitates and can be collected free of the other soluble components of
milk including whey proteins (see Swartz, Encyclopedia of Food Science and Technology, W.
H. Hui, editor, Wiley & Sons, 1991, Volume 1, pages 310-318). In a variation of the
precipitation technology, Connelly (U.S. Patent 4,376,020) showed that the whey proteins
could be made to interact with casein by treating the milk with alkaline and acid pH
30 adjustments. The whey-casein complex thus prepared could be precipitated near the
isoelectric pH of casein and the precipitated complex was collected and washed free of other
soluble components. Grafferty and Mulvihill (J. Soc. Dairy Technology, 40, 82-85, 1987)
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reported on the recovery of milk proteins by acid precipitation (pH 4.6) of casein and whey
protein complexes formed by heating milk at an alkaline pH. The insoluble acid precipitates
are made into functional ingredients for foods by neutralizing with food grade alkaline agents.
Another type of precipitated whey-casein complex is described by DeBoer (U.S. Patent
5 3,882,256) wherein milk is heated to greater than 90°C to form the whey-casein complex.
Calcium chloride is added to the heated milk to precipitate the whey-casein complex, and the
precipitate is washed free of other soluble components from milk. Commercial ingredients
made by these precipitation and solubilization technologies are typically called "caseinate",
"total milk protein", "milk protein co-precipitate", or "milk protein isolate".
10 Alternatively, the whey protein and casein protein can simultaneously be separated
from the small molecular weight components of milk (lactose, soluble minerals, peptides,
nucleic acids, etc.) using porous membrane filters in a process called ultrafiltration (UF). Milk
proteins are concentrated by applying pressure to the milk to force water and low molecular
weight components through the porous membrane filter while the proteins, fat, and insoluble
15 minerals are retained. Material passing through the membrane is termed the permeate, and
material not passing through the membrane is termed retentate. Typically, milk proteins are
concentrated by UF to a concentration two- to five-fold over the level in the starting milk.
There is a limit to the potential concentration due to the viscosity of the retentate and the
dynamics of the membrane filtration process.
20 Diafiltration (DF) is a similar membrane filtration process wherein water or other
diluent is added to the concentrated retentate at or about the same rate that the permeate is
removed. Thus, the volume of the retentate may not change much during the process of
diafiltration, but the low molecular weight materials are continuously removed from the high
molecular weight components in the retentate.
25 In the process described by Buhler, at al (U.S. Patent 4,125,527) ordinary milk, heated
milk, milk plus added whey, and milk adjusted to an acidic pH to enhance the removal of
otherwise insoluble calcium salts, were processed by ultrafiltration and diafiltration techniques
to concentrate and separate the whey and casein in the retentate using a membrane designed to
retain components greater than 10,000 molecular weight.
30 The process described in our invention provides an enhanced separation of small
molecular weight and large molecular weight components of milk by adding alkali to adjust
the pH above the natural pH of milk and below about pH 10 and heating the composition. It is
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preferable that pH adjustment and heating precede cooling the milk and thereafter subjecting
the cooled milk to UF and/or DF at a near neutral pH or a slightly acidic pH. The described
treatment of milk prior to membrane filtration enhances the separation of small and large
molecular weight components and provides a filtration retentate that is a protein concentrate
5 with a composition and functional performance not otherwise provided by current processing
art. Furthermore, selection of processing conditions combined with selection of UF and DF
membranes (that is selection of the membrane porosity or molecular weight cut-off) provides
one or more permeate compositions with unique protein compositions, and these permeates
can be further processed using current art to provide unique nutritional and functional protein
10 ingredients.
Careful selection of the alkali and the acid used for the pH adjustments prior to UF and
DF can provide a retentate with a beneficially increased calcium to protein ratio suitable for
making nutritional compositions without the further addition of insoluble calcium salts that
tend to settle out or separate from balanced nutritional beverages. Also, by selection of the
15 alkali and acid, the calcium and phosphate content of the retentate can be lowered, relative to
the protein, giving a milk concentrate with reduced opacity or with a composition, for
instance, similar to cheese and thus providing a unique ingredient for that food application.
By selecting the alkali and heat treatments, the milk protein micelle structure can be modified
with the resulting protein concentrate made suitable for high viscosity applications or for foods
20 where thickening is desired.
It is the general object of the present invention to provide milk concentrates with
unique compositions, that is, compositions with unique ratios of the casein to whey proteins
and with unique ratios of minerals to protein, while employing the techniques of ultrafiltration
and diafiltration or at least to offer the public a useful choice.
25
Summary of the Invention
The invention broadly consists of a process for preparing a protein concentrate with
reduced lactose, from milk containing lactose, comprising:
adjusting the pH of said milk into the range of about 7.5 to 10.0;
30 heating the pH adjusted milk to a temperature in the range of about 60-90°C;
cooling the heated pH adjusted milk to a temperature in the range of about 5-55°C; and
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subjecting said cooled, pH adjusted milk to membrane filtration to separate a protein-
enriched retentate from a lactose enriched permeate.
Preferably the pH adjusted milk is heated for from 6 seconds to 30 minutes.
Preferably adjusting the pH is accomplished with an alkali selected from the group
5 comprising ammonia, hydroxides of sodium, calcium, magnesium and potassium and alkaline
salts including an alkaline metal phosphate, citrate or carbonate.
Preferably said cooled, pH adjusted milk is subjected to further pH adjusting into the
range of about 7.0 to 5.5.
Preferably the further pH adjustment is accomplished with an acid selected from the
10 group comprising hydrochloric, sulfuric, phosphoric, acetic, lactic and citric acids, and acidic
salts of the polyprotic acids.
Preferably the initial pH adjustment is into the range of about 7.5 to 8.5.
Preferably the further pH adjustment is to about 6.5 to 6.0.
Preferably the heating is carried out for about 2 to 15 minutes.
15 Preferably the heating temperature is in the range of 75 to 85°C.
Preferably the cooling temperature is to about 15°C.
Preferably the subsequent pH adjustment is to about 6.2.
Preferably the process is further characterized by drying the protein-enriched retentate
to commercial dryness.
20 Preferably the membrane filtration is ultrafiltration.
Preferably the process is further characterized by the step of diafiltration following
ultrafiltration.
Preferably the process is carried out on a continuous basis.
Preferably the process includes conducting said membrane filtration in the presence of
25 a calcium solubilizing agent.
Preferably said calcium solubilizing agent is a citrate salt.
Alternatively the process includes conducting said membrane filtration in the presence
of a calcium complexing agent.
Preferably said calcium complexing agent is a citrate ion.
30 Preferably the retentate of said membrane filtration is recovered.
Preferably the permeate of said membrane filtration is recovered.
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Preferably the process includes the additional step of drying said protein concentrate at
the end of said other steps.
The invention also consists of a membrane filtration process for obtaining a milk
protein concentrate from milk, the improvement in which comprises adjusting said milk to a
5 pH in the range of about 7.0 to 10.0 and heating said pH adjusted milk to a temperature in the
range of about 60-90°C.
Preferably said pH adjustment and heating are accomplished prior to membrane
filtration.
Preferably the filtration is ultrafiltration.
10 Preferably said pH adjustment and heating are accomplished after the membrane
filtration.
The invention also consists of a process for preparing from milk, a composition with an
increased calcium to protein ratio, comprising:
adjusting the pH of said milk into the range of pH 7.5 to 10.0 using a calcium
15 containing alkaline agent; and
adding a neutralizing acidulant to adjust the pH into the range of 7.0 to 5.5.
Preferably the calcium containing alkaline agent consists of calcium oxide or calcium
hydroxide.
Preferably magnesium oxide, magnesium hydroxide, or a magnesium salt is included
20 with the calcium containing alkaline agent.
Preferably the neutralizing acidulent is phosphoric, sulfuric, hydrochloric, citric, or
lactic acid or any alkaline metal salt or alkaline earth salt capable of lowering the pH of said
alkali treated milk.
Preferably the process includes the additional step of subjecting said composition to
25 membrane filtration.
Preferably the retentate of said membrane filtration step is recovered.
Preferably the permeate of said membrane filtration step is recovered.
Preferably the process includes the additional step of drying said composition to
commercial dryness.
30 The invention also consists of a process for preparing from milk, a milk protein
composition which, when dissolved in water at about 25 °C and at about 14% protein in the
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water, has a viscosity at least ten fold greater than the viscosity of a comparable, but untreated
milk protein composition, comprising:
adjusting the pH of said milk into the range of 9.0 to 10.0;
heating the pH adjusted milk in the range of 80 to 100°C;
5 cooling the heated, pH adjusted milk into the range of about 5-55°C;
adjusting the pH of said cooled composition into the range of pH 7.5 to 5.5; and
drying the cooled composition.
Preferably the cooled composition is subjected to concentrating of the protein portion
prior to drying.
10 The invention also consists in the product of any of the processes just defined.
In particularly preferred embodiment, nonfat milk, or any of the derivatives of "milk"
as described above, in fluid form, is alkalized to a pH above that of the ordinary pH of milk,
i.e., about pH 6.6, and approximately pH 10, the preferred pH being in the range of about 7.5
to 8.5. The alkaline pH allows for the partial solubilizing of the various protein fractions
15 present in the milk, without disrupting or destroying substantially the micelle structure of the
major milk proteins and insoluble salts of milk. The alkaline agent can be chosen from any of
those approved for food use by the Food Chemical Codex, the preferred alkaline agents being
sodium hydroxide, calcium hydroxide, magnesium hydroxide, or some combination thereof.
The composition is then heated to a temperature between 60°C and 90°C, the preferred
20 temperature being in the range of about 75°C to 85°C. It is believed that the combination of
temperature and alkaline treatment causes the whey proteins to associate with the caseins to
provide a complex not otherwise present in untreated milk. It is not necessary to hold the milk
composition at the elevated temperature for any specific period of time, although a holding
period of about 5 to 15 minutes is preferred.
25 After this holding period, the heated composition is then cooled to a temperature
between about 5°C and 25°C, the preferred temperature being approximately 15°C. The pH of
this composition is then adjusted to near neutral or to a slightly acidic pH, i.e., between about
pH 7.5 and pH 5.5, with the preferred pH being about pH 6.5 to 7.2, unless a low calcium
version of the invention is desired. Low calcium versions are produced when the pH prior to
30 ultrafiltration and diafiltration is slightly acidic, the preferred pH being about pH 5.5 to pH
6.2. The acidifying agent can be chosen from any of those approved for food use by the Food
Chemical Codex, the preferred acids being hydrochloric, phosphoric, citric, and sulfuric acids,
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with the selection being dependent upon economic choices and the desired composition and
functional properties, principally of the retentate, but also of the permeate.
The composition is then processed by otherwise conventional techniques using
ultrafiltration and diafiltration membranes, the preferred construction being a spiral wound
5 module, with a manufacturing specified molecular weight cut-off of between 10,000 and
150,000, the preferred molecular weight cut-off range being 30,000 to 70,000 for a high
recovery of the whey proteins with the casein and a preferred molecular weight cut-off less
than 50,000 for recovery of certain of the whey proteins in the permeate fraction.
Ultrafiltration or ultrafiltration combined with diafiltration results in the collection of a
10 retentate and one or more permeates. It is not necessary to concentrate the milk proteins in the
retentate, relative to total solids, to any specific level, the level of concentration being
dependent on the desired composition of this retentate and the intended use of the liquid or
subsequently dried milk protein concentrate. Typically, ultrafiltration, as a single process, is
continued until the volume of the retentate is between one-half and one-fifth of the original
15 fluid milk volume, this being referred to as a "Volume Concentration Factor" (VCF), of two
to five, respectively. For use of the processed concentrate in standardization of cheese milk,
processed cheese, or as an ingredient in frozen desserts and certain nutritional liquids, a VCF
of two to three is sufficient. Reduction of the lactose content of the retentate to be a minor or
relatively insignificant component of the concentrate is achieved by ultrafiltration and
20 diafiltration to a high VCF, 100 to 300, more preferably 150 to 200.
The protein content of the UF and DF permeates is dependent both on the pretreatment
of milk as described in this invention and the selection of the membrane. Permeates that are
substantially free of protein can either be disposed of, dried, or utilized in industrial
applications. Permeates containing proteins that, by the process of this invention, were not
25 interacted with the casein proteins can further be processed by precipitation techniques,
membrane processing, or ion exchange chromatography to concentrate or isolate the protein
component while the rest of the permeate can either be disposed of, dried, or utilized in
industrial applications. Permeates can be collected during the individual ultrafiltration and
diafiltration processing steps or the permeates from these two processing steps can be
30 combined.
Diafiltration may utilize water, salt solution, dilute carbohydrate solution, or other
appropriate diluents for the retentate with this diluent added to the retentate during the
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diafiltration processing at about the same rate that permeate is removed. The preferred diluent
is water and the preferred rate of addition to the retentate is the same as the rate of permeate
removal.
The proteins in the liquid retentates are present in different forms than the proteins in
5 comparable retentates resulting from UF and DF of untreated skim milk. In the present
invention, the protein of the retentate is present as a combination of the natural micelles of
milk, micelles of milk interacted with the whey proteins, whey protein aggregates, whey
protein in the natural form found in milk, and protein-mineral complexes, especially protein-
calcium complexes, resulting from the alkali and heat treatments. The retained protein of the
10 present invention demonstrates markedly different physical and functional properties
compared to those properties exhibited by the protein retentate obtained from untreated skim
milk. By selection of the conditions for treating milk, the physical and functional properties of
the retentate can be adjusted to be more opaque or less opaque than protein from untreated
milk, to be more heat stable or less heat stable than the proteins from untreated milk, to be
15 more viscous or less viscous, or to have more calcium or less calcium than the protein or
retentate obtained from UF and DF of untreated skim milk. The proportion of casein and
whey proteins in the retentate of the present invention can further be adjusted by adding dairy
whey or whey protein concentrate to the nonfat milk prior to subjecting the fluid to the process
of this invention, thus producing milk protein concentrates with a higher level of whey protein
20 than would be obtained from processing standard skim milk.
Careful selection of the acid and the final pH prior to UF and DF can result in altering
the ash content and the calcium to protein ratio of the retentate. Use of an acid that can
complex with or solubilize the calcium phosphate of milk, the preferred acid in this case being
citric acid, will result in a low ash content and a low calcium content in the retentate. Also,
25 adjusting the final pH before UF and DF to a value between 5.5 and 6.5, preferentially about
pH 6.2, will also result in a reduction of the ash content and a reduction of the calcium content
of the retentate. These retentates are less viscous, less opaque, and substantially more heat
stable than the retentate from untreated skim milk.
The retentate resulting from the present invention may be utilized as an ingredient in
30 food without further processing, or the retentate can be dried using conventional techniques.
Prior to drying, the retentate may be further concentrated by removing water through either an
evaporative or a membrane process.
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Analytical Methods and Definitions
The solids content of fluid samples was measured using a microwave solids analyzer
from CEM Corp., Model AVC 80. Protein content of fluid samples was measured using
Coomassie dye and the procedure described by Sigma Diagnostics, Catalog No. 6 10- A. The
5 protein content of powder samples was measured by a Kjeldahl technique for nitrogen
analysis. Lactose content of fluid samples was measured using the Phenol- Sulfuric acid
technique. Lactose content of powdered samples was measured by both the Phenol-Sulfiiric
acid technique and by High Pressure Liquid Chromatography (HPLC). Ash is the material
remaining after heating a powder sample to greater than 500°C. Calcium was measured by ion
10 coupled plasma photometry. The concentrations of specific whey proteins, alpha-lactalbumin,
and beta-lactoglobulin, in fluid permeates and retentates was measured using an HPLC
technique with a TSK 2000 SW XL column, phosphate buffer with NaCl, and UV detection at
214 nm. Monomelic alpha-lactalbumin and beta-lactoglobulin standards (Sigma Chemical)
were used in the quantification technique.
15 Flavor scores and the ranking of products for opacity and whiteness were provided by
an eight member trained sensory panel. Solubility was a measure of the amount of powder
dissolving in water at either 20°C (cold water solubility) or at 60°C. Heat stability was
assessed by recording the amount of insoluble protein after retorting a 5% solids sample at
250°F for five minutes. Dispersibility is a measure of the time (in seconds) for 95% of 5
20 grams of powder to be evenly distributed as a water solution or suspension in 95 grams of
stirred water at 25°C. Viscosity was measured on suspensions or solutions in water at 15%
solids.
To demonstrate the effects of this invention on the efficient removal of lactose during
ultrafiltration and diafiltration, the lactose content of the retentate was plotted against a volume
25 concentration parameter defined by Rajagopalan and Cheryan (J. Dairy Sci., 74, 2435-2439,
1991). For ultrafiltration:
VCR = V /V
O R
30 where V = original volume
V = retentate volume
R
V p = permeate volume
9
= V -V
o p
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For diafiltration:
The lactose content of retentate (or permeate) was measured and compared to the lactose
concentration predicted by the Volume Parameter and rejection coefficient.
Volume Parameter = V d - ( 1/VCR)
= (V /V ) - (V /V )
v p r r <y
10
Also, lactose = (original lactose) x exp (-V (1 - R))
Where V q is defined above and R is the membrane rejection coefficient for lactose.
15 Brief Description of the Drawings
FIGURE 1 is a plot of lactose content of the retentate plotted against the calculated
Volume Parameter described by Rajagopalan and Cheryan, J. Dairy Sci., 74, 2435-2439,
1991). Data are from Example 1 where the milk, prior to UF and DF was treated by raising
the pH to 8.5, heating to 75 degrees C, cooling, and lowering the pH to 6.8 with sulfuric acid.
20 UF and DF on a 30,000 MWCO membrane. Two theoretical lines were calculated from the
initial lactose content, the Concentration Parameter, and assuming a rejection coefficient for
lactose of either 0 (solid line) or 0.3 (broken line).
FIGURE 2 is a plot of lactose content of the retentate plotted against the calculated
Volume Parameter described by Rajagopalan and Cheryan, J. Dairy Sci., 74, 2435-2439,
25 1991). Data are from untreated milk processed on the 30,000 MWCO membrane, like
Example 1. Two theoretical lines were calculated from the initial lactose content, the
Concentration Parameter, and assuming a rejection coefficient for lactose of either 0 (solid
line) or 0.3 (broken line).
FIGURE 3 is a plot of lactose content of the retentate plotted against the calculated
30 Volume Parameter described by Rajagopalan and Cheryan, J. Dairy Sci., 74, 2435-2439,
1991). Data are from Example 3 where the milk, prior to UF and DF was treated by raising
the pH to 7.5, heating to 87 degrees C, cooling, and lowering the pH to 6.8 with sulfuric acid.
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UF and DF on a 70,000 MWCO membrane. Two theoretical lines were calculated from the
initial lactose content, the Concentration Parameter, and assuming a rejection coefficient for
lactose of either 0 (solid line) or 0.3 (broken line).
FIGURE 4 is a plot of lactose content of the retentate plotted against the calculated
5 Volume Parameter described by Rajagopalan and Cheryan, J. Dairy Sci., 74, 2435-2439,
1991). Data are from untreated milk processed on the 70,000 MWCO membrane, like
Example 3. Two theoretical lines were calculated from the initial lactose content, the
Concentration Parameter, and assuming a rejection coefficient for lactose of either 0 (solid
line) or 0.3 (broken line).
10 FIGURE 5 is a scanning Electron Micrograph of spray dried UF, DF retentate powder
from milk preteated at pH 7.5 and 85° C, cooled, adjusted to pH 6.8 with sulfuric acid.
FIGURE 6 is a scanning Electron Micrograph of spray dried UF, DF retentate powder
from milk preteated at pH 9.5 and 65° C, cooled, adjusted to pH 6.8 with sulfuric acid.
FIGURE 7 is a scanning Electron Micrograph of spray dried UF, DF retentate from
15 milk without preteated or pH adjustments.
FIGURE 8 is a scanning Electron Micrograph of spray dried skim milk.
Detailed Description of the Preferred Embodiment
Example 1
20 156 kilograms (151.4 liters) of pasteurized, nonfat fluid milk was adjusted from the
natural pH of milk (approximately pH 6.5) to pH 8.5 by the addition of 1.86 kg of 2N sodium
hydroxide. The temperature of the mix was then increased to 75 °C, and the fluid held at that
temperature for five minutes. The vessel and the fluid were then cooled to 2.5 °C by the
addition of 10.9 kg of ice and the application of cooling water circulated through the vessel
25 jacket. The pH of the mix was adjusted to 6.8 by the addition of 2.1 kg of 0.5M sulfuric acid
while vigorously agitating the fluid. The temperature of the approximately 172.4 kg of fluid
was further reduced to approximately 15°C and the treated milk processed by ultrafiltration in
a Niro Ultrafiltration Pilot Plant model PA660A equipped with PES spiral wound membranes
with a molecular weight cut-off of 30,000 from Advanced Membrane Technology, Inc. By
30 ultrafiltration, the weight (or volume) was reduced to one-third of the original weight
accompanied by collection of 108.9 kg of permeate.
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Following the three-fold reduction in the fluid volume, diafiltration was started by
adding a total of approximately 190.5 kg of deionized water to the retentate at the same rate
that permeate was removed so as to maintain a constant volume of retentate. Following the
diafiltration process, the retentate was concentrated by an ultrafiltration process which reduced
the volume (or weight) by another factor of two. The final retentate was then collected by
draining the membrane module and flushing the module with deionized water. This
composition was then spray dried to produce a powdered ingredient.
In order to follow the course of processing, and in order to compare one pretreatment
to another, several samples of permeate and retentate were taken for analyses during
ultrafiltration and the subsequent diafiltration processing. Certain analyses were also
performed on the powder obtained after drying and on the composite UF permeate, the
composite DF permeate, and the retentates at the end of the UF and DF stages.
Table 1A shows more details of the volume and milk component concentration
measurements made during the processing of Example 1 and this table includes data on the
processing of untreated skim milk in the same membrane module.
12
WO 00/51440
PCT/NZ99/00026
TABLE 1A
PRETREATMENT, PROCESSING, AND YIELD
COMPARED TO AN UNTREATED CONTROL MILK
Example 1
Control
Milk (liters)
151.4
151.4
(kilograms)
156
156
2N NaOH (kilograms)
1.4
—
Alkaline pH
8.5
—
Temperature
75°C
—
Time
5 minutes
—
0.5M H2SO4 (pounds)
6
—
Final pH
6.8
6.6
UF permeate (kg)
113.9
108.9
UF retentate (kg)
54.4
54.4
DF permeate (kg)
222.3
225
DF diluent (kg)
222.3
225
UF VCF
3
3
DF equivalent VCF
60
60
Second UF VCF
2
2
Total equivalent VCF
360
360
Retentate protein (grams)
5360
5350
UF permeate protein (grams)
215
260
Retentate protein yield (%)
96
95
Removal of lactose from the retentate of milk treated by this invention is shown in Figure 1
and removal of lactose from untreated skim milk using the same membrane filtration
5 technique is shown in Figure 2.
The data in each figure are accompanied by two theoretical lines for lactose removal by
membrane filtration calculated from equations adopted from Rajagopalan and Cheryan (see
methods above). The theoretical lactose concentration in the retentate is dependent on the UF
and DF volume measurement and also on an assumed rejection coefficient for lactose.
13
WO 00/51440
PCT/NZ99/00026
Rejection coefficients generally range from zero to one with a value of zero assigned to
components that pass through the membrane unaffected by the membrane properties and a
value of one assigned to large components which do not pass through the membrane at all.
For the treated milk of this invention, the rejection coefficient for lactose (see Figure 1)
appears to be approximately zero, that is, the removal of lactose from the retentate is not
inhibited by the membrane or by coating of the membrane by the proteins of the retentate.
Within experimental error, the rejection coefficient for lactose for the untreated milk (Figure
2) is also about zero.
The composition, functional properties, and flavor scores for the powder produced by
the Example 1 process and a powder produced from untreated skim milk are shown in Table
IB.
TABLE IB
POWDER COMPOSITION AND PROPERTIES
FOR UF AND DF TREATED AND UNTREATED MILKS, 30 K MEMBRANES
Treatment
Powder Composition
Powder Properties
<
Na
EE
Cu
8.5
O
o
B
>—
CD
E
<u
H
75
a
o
89.2
vo
cN
0>
zn
O
o
0.5
<
7.3
h> Calcium %
o
<u
CO
*co
<u
GO
5
45
U
o
O
CM
©
CO s
92
U
o
O
IB
o
CO
99
ST 72
e o
^ £:
o ^
o '
33
<D
i—
O
O
CO
o
>
7.0
6.8
90.1
0.1
6.5
2.1
75
78
98
11
6.4
Compared to the product resulting from untreated skim milk, the product made by the
present invention has approximately the same composition, but has the unexpected advantages
of a more rapid cold water solubility and a higher, more desirable flavor score. Rapid cold
water solubility is advantageous when the ingredient is used as a part of a powdered nutritional
beverage mix, when the ingredient is used to supplement milk for cheesemaking, and when the
ingredient is used in other food applications that require full dissolution of the protein
ingredient in order to provide aesthetic and functional performance.
14
WO 00/51440
PCT/NZ99/00026
Example 2
151.4 liter samples of pasteurized skim milk were individually treated by the sequence
of processing steps described in Example 1 and using the alkali, temperature, and acid
treatments described in Table 2A.
TABLE 2A
MILK TREATMENT AND PROCESS VARIABLES
Membrane a
Alkali b
pH c
Temperature 0 *
Acid e
Total
VCFS
A
30 K
Na
7.5
75
SO
4
6.8
380
B
30 K
Na
7.5
85
SO
4
6.8
380
C
30 K
Na
8.5
65
so
4
6.8
370
D
30 K
Na
8.5
75
SO
4
6.8
360
E
30 K
Na
8.5
85
SO
4
6.8
460
F
30 K
Na
9.5
65
SO
4
6.8
380
G
30 K
Na
9.5
65
so
4
6.8
380
H
30 K
Na
9.5
85
so
4
6.8
400
I
30 K
None
NA
NA
None
NA
390
J
30 K
None
NA
NA
None
NA
390
a Membrane molecular weight cut-off 30 K = 30,000
b Type of alkali used to raise the milk pH Na = NaOH, Ca = Ca(OH) 2
c pH after alkali addition at 25 °C
d Temperature to which the alkalized milk was raised and held for 5 minutes
e Type of acid used to lower the pH, S0 4 = sulfuric acid, Citric = citric acid,
P0 4 = phosphoric acid
f pH after acid addition and before UF and DF
g Total effective Volume Concentration Factor after UF and DF and before drying
The treated milks were ultrafiltered and diafiltered in the same fashion as described in
Example L All of the treated milks (Table 2 A, samples A through H) and the untreated skim
milk in this example (Table 2A, samples I and J) were processed using a 30,000 molecular
weight cut-off, spiral wound membrane module. The membrane module was thoroughly
cleaned between each sample that was processed by flushing the module with caustic, water,
WO 00/51440
PCT/NZ99/00026
acid, water, alkaline protease, and water. Samples were taken for analysis during the UF and
DF processing, and a sample of the powdered product from spray drying each of these samples
was also taken for analysis. The compositions, solubility, heat stability, viscosity at 15%
solids, flavor evaluation, and the specific whey protein content of the UF and DF permeates
for the treated milks and the untreated milk samples are shown in Table 2B.
TABLE 2B
POWDER COMPOSITIONS AND PROPERTIES
FOR UF AND DF TREATED MILKS, 30 K MEMBRANES
Treatment
Powder Composition
Powder Properties
Alkali
55
a.
Temperature (°C)
Protein %
Lactose %
Ash %
Calcium %
Dispersibility (sec)
Solubility % @20°C
Solubility % @ 60°C
^ \
CO c
O ^
o *~
CO ^
> 1
Flavor Score
A
Na
7.5
75
89.3
0.6
7.2
2.2
60
99
100
17
6.4
B
Na
7.5
85
90.7
0.4
7.0
2.2
45
82
90
44
6.0
C
Na
8.5
65
90.3
0.5
7.1
2.1
60
92
99
30
6.6
D
Na
8.5
75
89.2
0.5
7.3
2.2
45
92
99
33
7.0
E
Na
8.5
85
88.6
0.3
7.5
2.2
75
77
100
21
6.1
F
Na
9.5
65
90.1
0.1
6.7
2.3
60
79
90
36
6.3
G
Na
9.5
65
90
0.1
6.8
2.3
60
80
93
51
6.6
H
Na
9.5
85
89.4
0.5
7.7
2.4
120
95
82
133
5.9
I
6.8
89.3
0.3
6.7
2
45
74
93
12
5.9
J
6.8
90.1
0.1
6.5
2.1
75
78
98
11
6.4
nd = not determined by assay.
Evaluation of the composition and properties of both the resulting powder and the
permeates for the effects of the pH treatment and the temperature treatment shows that:
concentrates prepared from milk treated at a high pH are more viscous, less heat stable, harder
to disperse and less soluble than the concentrate prepared from milk treated at pH 7.5 or 8.5;
16
WO 00/51440
PCT/NZ99/00026
concentrates made from a high temperature treatment of the milk were also more viscous and
less readily soluble than concentrates made from milk treated at lower temperature;
concentrates from milk treated at pH 8.5 and at moderate temperature (65 and 75°C) had the
best flavor score, were easy to disperse and were the most soluble at 20°C, but other treatment
5 conditions may be selected based on the desired attributes of the ingredient.
Example 3
156 kg (151.4 liters) of pasteurized, nonfat fluid milk was adjusted from the natural pH
of milk (approximately pH 6.5) to pH 7.5 by the addition of 1.2 kg of 2N sodium hydroxide.
The temperature of the mix was then increased to 85°C, and the fluid held at that temperature
10 for five minutes. The vessel and the fluid were then cooled to 25°C by the addition of 10.9 kg
of ice and the application of cooling water circulated through the vessel jacket. The pH of the
mix was then adjusted to 6.8 by the addition of 0.86 kg of 0.5M sulfuric acid while vigorously
agitating the fluid. The temperature of the approximately 163.3 kg of fluid was further
reduced to approximately 15°C and the treated milk processed by ultrafiltration in a Niro
15 Ultrafiltration Pilot Plant model PA660A equipped with PES spiral wound membranes with a
molecular weight cut-off of 70,000 from Snyder Filtration. By ultrafiltration, the weight (or
volume) was reduced to one-third of the original weight accompanied by collection of 108.9
kg of permeate.
Following the three-fold reduction in the fluid volume, diafiltration was started by
20 adding a total of approximately 190.5 kg of deionized water to the retentate at the same rate
that permeate was removed so as to maintain a constant volume of retentate. Following the
diafiltration process, the retentate was concentrated by an ultrafiltration process which reduced
the volume (or weight) by another factor of two. The final retentate was then collected by
draining the membrane module and flushing the module with deionized water. This
25 composition was then spray dried to produce a powdered ingredient.
Table 3A shows more details of the volume and milk component concentration
measurements made during the processing of Example 3, and this table includes data on the
processing of untreated skim milk in the same membrane module.
WO 00/51440
PCT/NZ99/00026
TABLE 3A
PRETREATMENT, PROCESSING, AND YIELD
COMPARED TO AN UNTREATED CONTROL MILK
Example 1
Control
Milk (liters)
151.4
151.4
(kilograms)
156
156
2N NaOH (kilograms)
1.4
0.45
Alkaline pH
7.5
—
Temperature
87°C
—
Time (minutes)
5
—
0.5M H 2 S0 4 (kilograms)
2
—
Final pH
6.8
6.8
UF permeate (kilograms)
108.9
108.9
UF retentate (kilograms)
54.4
54.4
DF permeate (kilograms)
222.3
222.3
DF diluent (kilograms)
222.3
222.3
UF VCF
3
3
DF equivalent VCF
33
33
Second UF VCF
2
2
Total equivalent VCF
200
200
Retentate protein (grams)
5600
5320
UF permeate protein (grams)
210
380
Retentate protein yield (%)
96
93
Removal of lactose from the retentate of milk treated by this invention is shown in Figure 3
and removal of lactose from untreated skim milk using the same membrane filtration
5 technique is shown in Figure 4. The data in each figure are accompanied by two theoretical
lines for lactose removal by membrane filtration calculated from equations adopted from
Rajagopalan and Cheryan (see methods above). The theoretical lactose concentration in the
retentate is dependent on the UF and DF volume measurement and also on an assumed
rejection coefficient for lactose. Rejection coefficients generally range from zero to one with a
18
WO 00/51440
PCT/NZ99/00026
value of zero assigned to components that pass through the membrane unaffected by the
membrane properties and a value of one assigned to large components which do not pass
through the membrane at all. For the treated milk of this invention, the rejection coefficient
for lactose (see Figure 3) appears to be approximately zero, that is, the removal of lactose from
the retentate is not inhibited by the membrane or by coating of the membrane by the proteins
of the retentate. Within experimental error, the rejection coefficient for lactose for the
untreated milk (Figure 4) is also about zero.
The composition, functional properties, and flavor scores for the powder produced by
the Example 3 process and the powder produced from untreated skim milk are shown in Table
3B.
TABLE 3B
POWDER COMPOSITION AND PROPERTIES
FOR UF AND DF TREATED AND UNTREATED MILKS, 70 K MEMBRANES
Treatment
Powder Composition
Powder Properties
Alkali
32
c
Temperature (°C)
Protein %
Lactose %
Ash %
Calcium %
Dispersibility (sec)
Solubility % @ 20°C
Solubility % @ 60°C
Viscosity (cP)
((a). 15% solids)
Flavor Score
Na
7.5
85
88.3
1.4
7.6
2.3
45
94
95
104
5.8
6.8
88.0
1.1
6.5
2.4
30
80
97
16
6.1
Compared to the product resulting from untreated skim milk, the product made by the present
invention has approximately the same composition, but lower lactose, and, as in Example 1,
has the unexpected advantages of a more rapid cold water solubility and a higher viscosity
when dissolved in water. The higher viscosity is an advantage in providing "body" and an
improved, less watery mouth feel to liquids.
Example 4
151.4 liter samples of pasteurized skim milk were individually treated by the sequence
of processing steps described in Example 3 and using the alkali, temperature, and acid
treatments described in Table 4 A.
19
WO 00/51440
PCT/NZ99/00026
TABLE 4A
MILK TREATMENT AND PROCESS VARIABLES
Membrane 3
Alkalib
pH c
Temperature^
Acid e
pH f
Total
VCFS
A
70 K
NaOH
7.5
87
so 4
6.8
200
B
70 K
NaOH
8.5
65
so 4
6.8
200
c
70 K
O.J
/Z>
£i Q
0.6
O AA
200
D
70 K
NaOH
8.5
85
so 4
6.8
200
E
70 K
NaOH
9.5
65
SO4
6.8
200
F
70 K
NaOH
9.5
87
SO4
6.8
200
G
70 K
NaOH
6.8
87
NA
NA
200
H
70 K
6.8
NA
NA
NA
200
a Membrane molecular weight cut-off 30 K = 30,000
5 b Type of alkali used to raise the milk pH Na « NaOH, Ca = Ca(OH)
c pH after alkali addition at 25°C
d Temperature to which the alkalized milk was raised and held for 5 minutes
e Type of acid used to lower the pH, S0 4 = sulfuric acid, Citric - citric acid,
P0 4 = phosphoric acid
10 f pH after acid addition and before UF and DF
g Total Volume Concentration Factor after UF and DF and before drying
The treated milks were ultrafiltered and diafiltered in the same fashion as described in
Example 3. All of the treated milks (Table 4 A, samples A through G) and the untreated skim
milk in this example (Table 4A, sample H) were processed using a 70,000 molecular weight
15 cut-off, spiral wound membrane module. The membrane module was cleaned by flushing the
module with caustic, water, acid, water, alkaline protease, and water. Samples were taken as
in Examples 1 through 3 during the UF and DF processing, and a sample of the powdered
product from spray drying each of the retentates was also taken for analysis. The
compositions, solubility, heat stability, viscosity, and flavor evaluation for samples from the
20 treated milks and the untreated samples of this example are shown in Table 4B.
20
WO 00/51440
PCT/NZ99/00026
Evaluation of the composition and properties of the spray dried, retentate powders for
the effects of the pH treatment and the temperature treatment applied to the milk prior to UF
and DF is shown in Table 4B.
5 TABLE 4B
POWDER COMPOSITION AND PROPERTIES
FOR UF AND DF TREATED MILKS, 70 K MEMBRANES
Treatment
Powder Composition
Powder Properties
Alkali
X
a.
Temperature (°C)
Protein % (db)
Lactose %
Ash %
Calcium %
Dispersibilily (sec)
Solubility % @20°C
Solubility % @ 60°C
Viscosity
(@ 15% solids)
Flavor Score
A
Na
7.5
85
88.3
1.4
7.6
2.3
45
94
95
104
5.8
B
Na
8.5
65
1.0
8.0
2.3
45
93
94
46
6.6
C
Na
8.5
75
88.2
1.4
7.1
2.2
45
98
96
31
6.4
D
Na
8.5
85
86.3
0.9
7.7
2.5
120
100
98
155,000
6.4
E
Na
9.5
65
89.3
1.3
7.0
2.1
45
93
99
18
6.5
F
Na
9.5
87
85.2
1.2
7.9
2.6
120
94
94
gelled
5.5
G
Na
6.8
87
87.8
0.9
9.1
2.5
120
80
89
190,000
6.1
H
6.8
88.0
1.1
6.5
2.4
30
80
97
16
6.1
All of the powders in this example have high protein, low lactose, and high calcium contents.
10 The powders from milk treated with alkali at the lowest temperature (65°C) dispersed easily
into water at about the same rate as the control powder (sample H) made without alkali or
temperature pretreatment. The cold water solubility (percent soluble at 20°C) for all of the
powders from alkali treated milk was improved over the cold water solubility of the control.
This improvement in solubility will provide for improved utility of the retentate powder from
15 this invention in dry powder nutritional drink mixes and for use in fortifying cheese milk,
21
WO 00/51440
PCT/NZ99/00026
since these applications, as well as others, require that the ingredients are fully soluble,
functional, and visually attractive.
From Table 4B, it is also apparent that the viscosity of 15% solutions of the retentate
powders could be altered in comparison to the viscosity of the control powder. The viscosity
5 of the resulting 15% powder solution (prepared hot and cooled to 25°C) increased with
increases in both the pH and the temperature of the alkali treatment. Surprisingly, some
conditions for pretreatment of the milk resulted in powders that could be used for very high
viscosity applications. The improved, highly viscous ingredients of this invention can be
utilized to impart "body" or "less watery" mouthfeel to liquid and semi-solids, and can be
10 utilized in high moisture and lowfat food applications.
The trained panel flavor scores were highest for retentates prepared from low
temperature treatments at all of the alkaline pHs shown in Table 4B. The flavor scores for the
retentates from alkali treatment at pH 8.5 and 9.5 show an improvement over the flavor score
of the retentate from untreated standard milk. It should be noted that the flavor score for the
15 powder from untreated milk is already high (value is 6.1, maximum score is 7.0) and any
improvement will allow the ingredients to be utilized in flavor-sensitive applications and in
applications where a high protein content is required.
Example 5
151.4 liter samples of pasteurized skim milk were individually treated by the sequence
20 of processing steps described in Example 1 and using the alkali, temperature, and acid
treatments described in Table 5 A.
22
WO 00/51440
PCT/NZ99/00026
TABLE 5A
Membrane
Alkali
PH
Temp (°C)
Acid
PH
Total
VCF
A
30 K
NaOH
7.5
85
citric
6.8
380
B
30 K
Ca(OH) 2
7.5
85
sulfuric
6.8
380
C
30 K
Ca(OH) 2
8.5
75
phosphoric
6.8
360
D
30 K
Ca(OH) 2
8.5
75
phosphoric
6.8
120
E
70 K
Ca(OH) 2
8.5
75
phosphoric
6.8
140
F
70 K
Ca(OH) 2
8.5
75
Na phosphate
6.8
200
& phosphoric
G
70 K
Ca(OH) 2
9.5
65
phosphoric
6.8
200
H
70 K
NaOH
9.5
75
citric
6.2
200
The treated milks were ultrafiltered and diafiltered in the same fashion as described in
Example 1. The treated milks of Table 5 A were processed using either a 30,000 or a 70,000
molecular weight cut-off, spiral wound membrane module as designated in Table 5A. The
membrane module was thoroughly cleaned between each sample that was processed by
flushing the module with caustic, water, acid, water, alkaline protease, and water. Samples of
the powdered product from spray drying each of the retentate samples were taken for analysis.
The compositions, solubility, heat stability, viscosity at 15% solids, and flavor evaluations are
shown in Table 5B.
23
WO 00/51440
PCT/NZ99/00026
TABLE 5B
POWDER COMPOSITION AND PROPERTIES
FOR UF AND DF TREATED MILKS, 30 K MEMBRANES
Treatment
Powder Composition
Powder Properties
Membrane
Alkali
c
o
o
C3
U.
D
£
£-<
Protein %
Lactose %
Ash %
Calcium %
Dispersibility (sec)
Solubility % @ 20°C
Solubility % @ 60°C
Viscosity (cP)
Flavor Score
A
30
Na
7.5
85
91
0.4
7.0
2.2
45
82
90
44
6.0
B
30
Ca
7.5
85
88
0.3
8.6
3
30
75
90
17
6.0
C
30
Ca
8.5
75
84
0.4
9.5
3.3
30
68
83
15
5.8
D
30
Ca
8.5
75
87
0.7
9.5
3.3
45
85
87
15
5.9
E
70
Ca
8.5
75
84
1.3
9.9
3.4
45
37
91
12
5.5
F
70
Ca
8.5
75
86
0.9
9.6
3.5
30
53
91
19
6.4
G
70
Ca
9.5
65
84
0.9
11.8
3.6
30
49
75
11
5.9
H
70
Na
9.5
75
91
1.2
6.8
2.2
75
91
92
42
6.4
Also, see Tables 2A, 2B, 4A, and 4B for the analysis of untreated milk and for some of the
below mentioned comparisons of the properties from this example.
The use of calcium hydroxide as the alkaline agent for pH increase results in an
increase in the calcium content of the retentate in proportion to the amount of calcium
hydroxide used for the pH increase. A significant portion of the calcium used to adjust the pH
upwards has been recovered in the retentate from each of the calcium hydroxide treated milks.
From calcium recovery calculations, virtually all of the 56 grams of calcium (used as calcium
hydroxide) added in adjusting the pH to 7.5 was recovered in the retentate of example 5B.
Approximately 70% of the 90 grams of calcium (added as calcium hydroxide) used to adjust
the pH to 8.5 or 9.5 was recovered in the retentates of examples 5C and 5G. The calcium
added to the milk for the pH adjustment in the improved ingredients is advantageously
24
WO 00/51440
PCT/NZ99/00026
retained due either to binding to the protein or due to being made insoluble from adding either
sulfuric or phosphoric acid during the pretreatment of milk before membrane processing.
The calcium level of the retentate can be adjusted to a level lower than that of the
retentate of the control, untreated milk by using citric acid as the pH lowering agent (examples
5 A and 5H), or by lowering the pH below the natural pH of milk in order to solubilize the
natural calcium component of the retentate (example 5H). This invention thus results in being
able to adjust the calcium content of the retained high protein ingredient in a manner and to an
extent not otherwise provided by current art.
The powders resulting from spray drying retentates after pH adjustment with calcium
hydroxide appear, in comparison to comparable powders produced using sodium hydroxide, to
be more readily dispersible into water, to be less soluble in water at both 20°C and 60°C, to be
less heat stable, and to make solutions which are less viscous. The flavor scores of the
retentates from calcium hydroxide treated skim milk are reduced in comparison to flavor
scores of the retentates from sodium hydroxide treated milk principally due to having a
slightly more chalky mouthfeel.
Example 6
Pasteurized, fluid skim milk was concentrated two-fold by ultrafiltration using a
30,000 molecular weight cut-off membrane module. The concentrate contains about 50% of
the original lactose and almost all of the original protein in one-half of the original volume.
The concentrate pH was adjusted from the original pH 6.6 to pH 8.5 using 2N sodium
hydroxide. The temperature of the mix was then increased to 75°C, and the fluid held at that
temperature for more than five minutes, after which the temperature was adjusted back to
25°C. The pH of this alkali and heat treated mix was then adjusted to pH 6.8 by the addition
of 0.5M sulfuric acid while vigorously agitating the fluid. The temperature was further
reduced to approximately 15°C and the treated concentrate processed by a combination of
ultrafiltration and diafiltration using PES spiral wound membranes with a molecular weight
cut-off of 70,000. The membrane processing was completed at an equivalent VCF of 220.
The final retentate was spray dried to a powder, and the powder was analyzed as described in
the examples above.
25
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TABLE 6
POWDER COMPOSITION AND PROPERTIES
FOR UF AND DF TREATED MILK, 70 K MEMBRANES
Treatment
Powder Composition
Powder Properties
Alkali
X
& -
Temperature (°C)
Protein % (db)
Lactose %
Ash %
Calcium %
Dispersibility (sec)
Solubility % @ 20°C
Solubility % @ 60°C
Viscosity (cP)
Flavor Score
Na
8.5
75
89.0
.,
nd
nd
45
90
100
191
6.7
Table 6 summarizes the composition and the physical properties of the powdered
retentate. This example is similar to example 4C regarding the alkali and heat treatment, but
5 differs from 4C in the sequence of UF and pH adjustment. In 4C, the milk was alkali-heat
treated before UF, and here, the milk was first concentrated two-fold before the alkali-heat
treatment. The retentate of this example can also be compared to the retentate from untreated,
standard milk. Example 4H. The dispersibility of the three samples is about the same, but the
viscosity of a 15% suspension of Example 6 and Example 4C is higher than the viscosity of
10 the retentate from standard milk. The cold water solubility and the flavor score for Example 6
is also improved over the properties of the retentate from untreated milk, as is the retentate
from Example 4C. Minor adjustments to the retentate protein properties are possible from
careful selection of the processing sequence as well as the conditions for alkali and heat
treatments and the selection of the membrane. Process economics may favor the pre-
15 concentration of the milk by membrane or evaporative processing benefits can be continued
through use of this invention.
26
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PCT/NZ99/00026
Example 7
Pasteurized skim milk was processed in a continuous system for alkali addition, heat
treatment, cooling, neutralization with acid, ultrafiltration, and diafiltration. One alkali-heat
treatment of the invention (7A) was adjusted to pH 7.5 with sodium hydroxide, heating to
85°C, cooling to 25°C, and neutralization to pH 6.8 with sulfuric acid. Another alkali-heat
treatment (7B) was adjustment to pH 9.5 with sodium hydroxide, heating to 65°C, cooling to
25°C, and neutralization to pH 6.8 with sulfuric acid. In a third trial (7C), untreated skim milk
was processed in the continuous UF and DF module. In all cases, the UF and DF module
utilized 10,000 molecular weight cut-off membranes and the milks were membrane processed
to give retentates with the re-trials having less than 2% lactose.
Properties of the three retentates are shown in Table 7.
TABLE 7
POWDER COMPOSITION AND PROPERTIES
FOR UF AND DF TREATED MILKS, 10 K MEMBRANES
Treatment
Powder Composition
Powder Properties
Alkali
15.
Temperature (°C)
Protein % (db)
Lactose %
Ash %
Calcium %
Dispersibility
(seconds)
Solubility % @20°C
Solubility % @ 60°C
Heat Stability
(retorted)
Viscosity (@ 15%
solids)
Flavor Score
A
Na
7.5
85
89.8
1.2
7.5
2.4
45
97
100
97
22
NA
B
Na
9.5
65
88.7
1.7
7.7
2.4
60
97
90
95
26
6.3
C
6.6
90.1
1.7 |
7.2
2.3
60
83
96
90
13
6.3
Example 8
To 151.4 liters of skim milk, having about 5,500 grams of protein, was added 1.6
kilograms of powdered whey protein concentrate having about 1,200 grams of protein. The
fluid was adjusted to pH 7.5 with sodium hydroxide, heated to 65°C, held for 15 minutes,
cooled to 25°C, and adjusted to pH 6.4 using citric acid. The treated mix was cooled to 15°C
and processed by UF and DF to a combined equivalent VCF of about 400 using a 30,000
molecular weight cut-off membrane module.
27
WO 00/51440
PCT/NZ99/00026
Properties of the retentate powder from Example 8 are shown in Table 8. Use of citric
acid for pH adjustment and UF and DF at pH 6.4 resulted in a low calcium powder compared
to the control, untreated milk of example 21 and 2J.
TABLE 8
POWDER COMPOSITION AND PROPERTIES
FOR UF AND DF TREATED MILK, 70 K MEMBRANES
Treatment
Powder Composition
Powder Properties
Alkali
a*
o
o
<U
s
CD
Cm
£
53
Protein % (db)
Lactose %
Ash%
Calcium %
Dispersibility (seconds)
Solubility % @20°C
Solubility % @ 60°C
Heat Stability (retorted)
Viscosity
CO
GO
0 s
1
Flavor Score
A
Na
7.5
65
90.3
0.4
5.9
1.8
120
90
96
na
11
5.6
*
• pH prior to UF and DF was 6.4 adjusted using citric acid. Starting fluid was milk
• with added whey protein.
It is estimated that approximately 95% of the added whey protein remains in the UF,
DF retentate. Because of the high level of amino acids essential to human growth and
maintenance, this retentate complex with its good flavor and high solubility should be an
excellent ingredient for nutritional supplementation.
Example 9
Samples of milk were treated by the conditions outlined in Table 9 and then membrane
filtered by a combined UF and DF process using the membranes and the equivalent VCF
reported in Table 9. The composition and notable physical or functional properties are also
reported in Table 9.
28
WO 00/51440
PCT/NZ99/00026
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29
WO 00/51440
PCT/NZ99/00026
A very low calcium retentate was processed by using a citrate salt in the DF diluent to
continuously solubilize native milk calcium for removal to the permeate. Membranes with
10,000, 30,000, and 100,000 molecular weight cut-offs could be used to give high yields of
protein and calcium in the retentates.
Observations on Example 9 Retentate Samples
Some very low calcium variations (9F and 9L) were prepared by UF and DF at low pH
and in the presence of calcium complexing citrate ions. These appear to have the highest
viscosity and should function like sodium caseinate in processed foods.
When dissolved in water, the most opaque white retentates were 9E, 9K, 9B, and 9A
with 9E and 9K being more opaque (white) than the others. The least opaque were 9G, 9J, and
9L. The low opacity retentates were from milk pretreated at high pH or retentates collected
during UF of slightly acidic milk. The opacity was restored by neutralizing the low pH retentate
with calcium hydroxide (sample 9E). Unexpectedly, this sample also had the highest cold water
solubility of this group; 100% soluble at 25°C. This product of the invention has attractive
features as an ingredient for nutritional foods and other applications where a functional milk
protein is needed.
Example 10
Skim milk, with a lactose content of about 60% of the solids, was treated by a combined
UF and DF membrane filtration process to reduce the lactose to less than about 1% to 2% of the
solids and this was used as the starting material for the process of this invention. The
concentrate contained about 1% of the original lactose and almost all of the original protein in
one-third to one-fourth of the original volume. It is not necessary to concentrate the milk
proteins in the retentate, relative to total solids, to any specific level, the level of concentration
being dependent on the desired composition of this retentate and the intended use of the liquid
or subsequently dried milk protein concentrate. The pH of the concentrate was adjusted from
the original pH 6.6 to pH 7.5 using 2N sodium hydroxide. The temperature of the mix was then
increased to 85°C, and the fluid held at that temperature for more than five minutes, after which
the temperature was adjusted back to 25°C. The pH of this alkali and heat treated mix was then
adjusted to pH 6.8 by the addition of 0.5M sulfuric acid while vigorously agitating the fluid. No
30
WO 00/51440
PCT/NZ99/00026
further membrane processing was undertaken. The composition was spray dried to a powder
and evaluated for performance characteristics.
The dried product from the alkali treatment of the invention had a cold water solubility
of 88% compared to 80% cold water solubility for the dried UF and DF processed control
untreated standard milk. The viscosity of 15% solids was 20 Centipose, or about the same as
that of the dried UF and DF processed control untreated standard milk (see Example 4H, Table
4). The properties of this example compare beneficially to those of the product of current art.
The product of the invention disperses easily in water (30 seconds for 95% of 5 grams of
powder to be evenly distributed as a water solution or suspension in 95 grams of stirred water at
25 °C) and water solutions of the product were opaque white. The product of this example is
comparable to the product of Example 4A where the starting material was ordinary milk and the
UF and DF processing was performed after the alkali treatment of the invention. The raw
material for the alkali treatment of the invention can be milk or milk that has been concentrated,
and the product of the invention can be dried for use as an ingredient, or the product can be used
as a liquid. Alternatively, the product of the invention may be concentrated and dried as an
ingredient or it may be concentrated and used as a liquid without loss of the benefits of the
invention.
Protein Content in UF and DF Permeates
The typical content of alpha-lactalbumin in milk is approximately 0.6 to 1.7 grams per
liter, or on the average approximately 1.2 grams per liter. Also, the typical content of beta-
lactoglobulin is approximately 3.0 grams per liter. 151.4 liters should contain approximately
180 grams of alpha-lactalbumin and 450 grams of beta-lactoglobulin. Analysis of the 108.9 kg
of UF permeate from Examples 3 and 4 using a 70,000 molecular weight cut-off membrane
shows approximately 40 grams of alpha-lactalbumin and 40 grams of beta-lactoglobulin in each
of the UF permeates. Table 10 shows the concentrations and proportion of the protein in the
permeate represented by alpha-lactalbumin and beta-lactoglobulin for a variety of milk
pretreatments and three types of membrane. The concentration of these two proteins in the
permeate was dependent upon both the alkali and heat pretreatment of the milk and on the
membrane used for UF and DF processing. The permeate proteins are shown in Table 10 for
both the ultrafiltration permeate, that is the permeate collected during the initial three-fold
concentration step, and the diafiltration permeate, that is permeate collected after concentration
and during membrane processing at a constant volume of retentate. Selection of the alkali,
31
WO 00/51440
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temperature, and membrane can be used to produce one or more permeates, with a unique, and
surprisingly high proportional content of alpha-lactalbumin compared to the proportion in milk
and compared to the proportion in permeate from the untreated milk samples, A, C, and L. For
instance, when the milk is treated at the higher temperatures (75°C or 85°C), regardless of the
5 pH, one obtains an ultrafiltration or diafiltration permeate with a much higher level of alpha-
lactalbumin as a percent of the total protein in the permeate in comparison to the permeate
proteins from untreated and unheated skim milk.
32
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TABLE 10
UF AND DF PERMEATE PROTEIN COMPOSITION
DEPENDENCE OF MILK TREATMENT
A/Till/ - Drn r* a o o /rnrlif i /Ann
Permeate Protein
Grams/liter
%
O
o
)cess
imin
>ulin
Reference
EC
Temperature (
Membrane Pr<
Total
A
Alpha-lactalbi
B
Beta-lactoglo!
(A + B)/T
A
A
6.8
25
UF 10
2.20
0.71
0.76
0.67
DF 10
2.65
0.44
0.53
0.32
r>
6.8
87
UF 10
2.14
0.77
0.72
0.69
DF 10
1.71
0.33
0.33
0.39
32
6.8
25
UF 30
2.40
0.66
0.78
0.60
u
9
7.5
75
UF 30
1.23
0.43
0.54
0.79
26
7.5
85
UF 30
r
14
8.5
65
UF 30
2.14
0.63
0.74
0.65
27
8.5
75
UF 30
1.76
0.59
0.68
0.72
IT
10
8.5
85
UF30
1.80
0.63
0.76
0.77
T
I
21
9.5
65
UF 30
2.04
0.59
0.73
0.65
T
J
20
9.5
65
UF 30
1.96
0.61
0.74
0.69
K
1
9.5
85
UF30
1.84
0.60
0.74
0.73
T
L
43
6.8
25
UF 70
1.97
0.34
0.36
0.36
DF 70
1.16
0.10
0.11
0.18
M
40
7.5
87
UF 70
0.87
0.33
0.32
0.75
DF 70
0.42
0.11 .
0.12
0.31
N
46
8.5
65
UF 70
0.87
0.33
0.32
0.75
DF 70
2.75
0.20
0.24
0.16
O
41
8.7
75
UF 70
1.04
0.30
0.33
0.61
DF 70
0.79
0.12
0.14
0.33
33
WO 00/51440
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TABLE 10
UF AND DF PERMEATE PROTEIN COMPOSITION
DEPENDENCE OF MILK TREATMENT (CONT)
Permeate Protein
Grams/liter
%
Reference
X
o.
O
o
CD
J—
u
<D
1
H
Membrane Process
Total
A
Alpha-lactalbumin
B
Beta-lactoglobulin
H
+
<
p
45
8.5
85
UF 70
1.09
0.32
0.34
0.61
DF 70
0.77
0.11
0.13
0.31
Q
42
9.5
65
UF 70
1.25
0.30
0.34
0.51
DF 70
1.08
0.12
0.14
0.24
R
44
9.5
87
UF 70
0.99
0.31
0.36
0.68
DF 70
0.76
0.12
0.16
0.37
It should be noted that the alpha-lactalbumin and beta-lactoglobulin contents of the
permeates listed in Table 10 are the measured content of the monomelic form of these two
proteins. Because of possible disulfide bond formation, these proteins, and especially beta-
lactoglobulin, may exist as dimers, trimers, or other higher ordered polymers. These polymeric
forms could not be distinguished using the HPLC and the analytical methods employed herein,
so the discoveries regarding the use of this invention are directed towards the specific recoveries
of the monomelic forms of alpha-lactalbumin and beta-lactoglobulin. It may be that a portion,
or even the majority, of the other permeate proteins making up the "total" level determination
from the HPLC chromatogram are polymers principally involving beta-lactoglobulin.
The discovery that there are less "other proteins" in the permeates of the ultrafiltered
milks treated by the invention at the higher temperatures (75°C and 85°C) while the recovery of
monomelic alpha-lactalbumin and beta-lactoglobulin appears to be at a fixed level, principally
dependent upon the choice of membrane porosity, supports an objective of the invention to have
more whey protein beneficially retained with the casein and the insoluble minerals. That is, a
34
WO 00/51440
PCT/NZ99/00026
lower level ot total protein m the permeate is a significant processing benefit provided by the
invention.
An unexpected finding from the permeate protein data shown in Table 10 is that the
monomelic alpha- lact albumin (and beta-lactoglobulin) recovery was highest in permeates from
processing with the 10,000 molecular weight cut-off membrane. The permeate concentration of
alpha-lactalbumin was highest when the 10,000 MWCO membrane filter was used and was
lowest when the 70,000 MWCO membrane was used, a result which was unexpected from prior
art.
Regression analyses on data for the 70,000 MWCO membrane to determine the effects
of the pH and temperature pretreatment of the milk on the recovery of alpha-lactalbumin as a
high percentage of the total proteins in the permeate showed that: 1) high pH treatment gives a
higher percent alpha-lactalbumin, 2) high temperature treatment gives a higher alpha-
lactalbumin percentage, and 3) there is a negative two-factor interaction of (pH x temperature).
None of these effects could have been predicted from the information on the current state of the
art regarding pH and temperature treatments of milk. One might expect closely similar effects
on the alpha-lactalbumin content of the permeate protein from 30,000, 10,000, and other
membrane processing modules.
It is well known that human milk is the most desirable nutritional fluid for nurturing
infants, and human milk contains a much higher level of alpha-lactalbumin than does bovine
milk or bovine whey produced by conventional techniques. It is the specific amino acid profile
of both human alpha-lactalbumin and bovine alpha-lactalbumin that provides for the desirable
nutritional attributes of this particular protein. The current invention provides a process for
making a desirable milk protein concentrate as a retentate from UF and DF treatment, and it
provides a highly desirable protein composition in the membrane filtration permeate from milk
that is first treated under the conditions of this invention.
Recovery of the alpha-lactalbumin enriched whey protein from the permeates of this
invention is possible using one or more of the current state of the art technologies involving
whey protein precipitation, whey protein complexing with carbohydrates and gums, trapping
and recovering the proteins using ion exchange media, or ultrafiltration using very low
molecular weight cut-off membrane modules so that the lactose and water are removed in the
permeate and the monomelic alpha-lactalbumin and beta-lactoglobulin are recovered in the
retentate.
35
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PCT/NZ99/00026
Retention of the Native Milk Protein Micelle and Alterations to the Micelle
Structure
The spray dried retentates from ultrafiltering and diafiltering milk pretreated at pH 7.5
and 85°C, milk pretreated at pH 9.5, 65°C (Example 7B)and untreated (control) milk, (Example
7C) were examined for protein aggregates and either retention or modification of the native milk
protein micelles by scanning electron microscopy (SEM). The four photomicrographs (Figures
5, 6, 7, and 8) are SEM photographs from the above mentioned powders and from untreated
nonfat skim milk, respectively. The skim milk SEM photograph (Figure 8) shows distinctive,
well separated micelles of approximately 0.1 micron diameter. The retentate from UF and DF
treatment of the control untreated skim milk (Figure 7) shows that the micelles from routine,
state of the an processing are aggregated to form a rather extensi ve matrix of protein. However,
skim milk that had been treated at pH 7.5 and at 85°C and then subsequently ultrafiltered and
diafiltered showed retention of distinctive, unaggregated micelles of protein and much smaller
aggregates of protein micelles than are shown from the retentate of untreated milk (compare
Figure 5 to 7). This retention of micelles and the appearance of only small aggregates of protein
micelles may account for the improved cold water solubility as a benefit of this invention. The
dried retentate from milk that had been pretreated at pH 9.5 and 65°C, Figure 6, shows very few
large individual micelles (of the order of .1 micron), but rather shows an extensive network of
0.02 to 0.05 micron diameter protein aggregates. These extended aggregates appear to be as
large or larger than the aggregates of the retentate from untreated milk (Figure 7). The retentate
with the aggregates of proteins reduced in size from the native micelle shows a new state,
different from native nonfat dry milk and different from the ultrafiltered retentate of untreated
milk. This extended matrix of protein may account for the high viscosity of retentates treated at
pH 9.5. Thus, the invention can result in the preservation of the milk micelle or can result in the
reduction of the micelle to perhaps submicelles with an apparent aggregation of these smaller
units together to form some type of protein matrix depending on the alkali and the temperature
treatment of the milk prior to UF and DF and subsequent drying.
36
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PCT/NZ99/00026
WHAT IS CLAIMED IS :
1 . A process for preparing a protein concentrate with reduced lactose, from milk
containing lactose, comprising:
adjusting the pH of said milk into the range of about 7.5 to 10.0;
heating the pH adjusted milk to a temperature in the range of about 60-90°C;
cooling the heated pH adjusted milk to a temperature in the range of about 5-
55 C C; and
subjecting said cooled, pH adjusted milk to membrane filtration to separate a
protein-enriched retentate from a lactose enriched permeate.
2. A process in accordance with claim 1 where the pH adjusted milk is heated for
from 6 seconds to 30 minutes.
3. A process in accordance with claim 1 or 2 where adjusting the pH is
accomplished with an alkali selected from the group comprising ammonia, hydroxides of
sodium, calcium, magnesium and potassium and alkaline salts including alkaline metal
phosphate, citrate or carbonate.
4. A process in accordance with any one of the preceding claims where said cooled,
pH adjusted milk is subjected to further pH adjusting into the range of about 7.0 to 5.5.
5. A process in accordance with claim 4 where the further pH adjustment is
accomplished with an acid selected from the group comprising hydrochloric, sulfuric,
phosphoric, acetic, lactic and citric acids, and acidic salts of the polyprotic acids.
6. A process in accordance with any one of the preceding claims where the initial
pH adjustment is into the range of about 7.5 to 8.5
7. A process in accordance with claim 4 or claims 5 or 6 when dependent from
claim 4 where the further pH adjustment is to about 6.5 to 6.0.
8. A process in accordance with any one of the preceding claims where the heating
is carried out for about 2 to 15 minutes.
9. A process in accordance with any one of the preceding claims where the heating
temperature is in the range of 75 to 85°C.
10. A process in accordance with any one of the preceding claims where the cooling
temperature is to about 15°C.
11. A process in accordance with claim 7 or any one of claims 8 to 10 when
dependent from claim 7 where the subsequent pH adjustment is to about 6.2.
12. A process in accordance with any one of the preceding claims and further
characterized by drying the protein-enriched retentate to commercial dryness.
13. A process in accordance with any one of the preceding claims where the
membrane filtration is ultrafiltration.
WO 00/51440
PCT/NZ99/00026
14. A process in accordance with claim 13 and further characterized by the step of
diafiltration following ultrafiltration.
15. A process in accordance with any one of the preceding claims carried out on a
continuous basis.
16. A process in accordance with any one of the preceding claims which includes
conducting said membrane filtration in the presence of a calcium solubilizing agent.
17. A process in accordance with claim 16 wherein said calcium solubilizing agent is
a citrate salt.
18. A process in accordance with any one of the preceding claims which includes
conducting said membrane filtration in the presence of a calcium complexing agent.
19. A process in accordance with claim 18 wherein said calcium complexing agent is
a citrate ion.
20. A process in accordance with any one of the preceding claims in which the
retentate of said membrane filtration is recovered.
21. A process in accordance with any one of the preceding claims which the
permeate of said membrane filtration is recovered.
22. A process in accordance with any one of the preceding claims which includes the
additional step of drying said protein concentrate at the end of said other steps.
23. In a membrane filtration process for obtaining a milk protein concentrate from
milk, the improvement comprising adjusting said milk to a pH in the range of about 7.0 to 10.0
and heating said pH adjusted milk to a temperature in the range of about 60-90°C.
24. A membrane filtration process in accordance with claim 23, wherein said pH
adjustment and heating are accomplished prior to membrane filtration.
25. A membrane filtration process in accordance with claim 23 or 24 wherein the
filtration is ultrafiltration.
26. A membrane process in accordance with claim 23 or 25 when dependent from
claim 23 wherein said pH adjustment and heating are accomplished after the membrane
filtration.
27. A process for preparing from milk, a composition with an increased calcium to
protein ratio, comprising:
adjusting the pH of said milk into the range of pH 7.5 to 10.0 using a calcium
containing alkaline agent; and
adding a neutralizing acidulant to adjust the pH into the range of 7.0 to 5.5.
28. A process in accordance with claim 27 where the calcium containing alkaline
agent consists of calcium oxide or calcium hydroxide.
38
WO 00/51440
PCT/NZ99/00026
29. A process in accordance with claim 27 or 28 where magnesium oxide,
magnesium hydroxide, or a magnesium salt is included with the calcium containing alkaline
agent.
30. A process in accordance with any one of claims 27 to 29 where the neutralizing
acidulent is phosphoric, sulfuric, hydrochloric, citric, or lactic acid or any alkaline metal salt or
alkaline earth salt capable of lowering the pH of said alkali treated milk.
31. A process in accordance with any one of the preceding claims 27 to 30 which
includes the additional step of subjecting said composition to membrane filtration.
32. A process in accordance with claim 3 1 wherein the retentate of said membrane
filtration step is recovered.
33. A process in accordance with claim 3 1 wherein the permeate of said membrane
filtration step is recovered.
34. A process in accordance with any one of claims 27 to 33 which includes the
additional step of drying said composition to commercial dryness.
35. A process for preparing from milk, a milk protein composition which, when
dissolved in water at about 25° C and at about 14% protein in the water, has a viscosity at least
ten fold greater than the viscosity of a comparable, but untreated milk protein composition,
comprising:
adjusting the pH of said milk into the range of 9.0 to 10.0;
heating the pH adjusted milk in the range of 80 to 100° C;
cooling the heated, pH adjusted milk into the range of about 5-55° C;
adjusting the pH of said cooled composition into the range of pH 7.5 to 5.5; and
drying the cooled composition.
36. A process in accordance with claim 35 wherein the cooled composition is
subjected to concentrating of the protein portion prior to drying.
37. A product produced according to the process of any one of claims 1 to 22.
38. A product produced according to the process of any one of claims 23 to 26.
39. A product produced according to the process of any one of claims 27 to 34.
40. A product produced according to the process of either of claims 35 or 36.
39
WO 00/51440
1 / 8
PCT/NZ99/00026
SUBSTITUTE SHEET (RULE 26)
WO 00/51440
2 / 8
PCT/NZ99/00026
SUBSTITUTE SHEET (RULE 26)
WO 00/51440
3 / 8
PCT/NZ99/00026
SUBSTITUTE SHEET (RULE 26)
WO 00/51440
5 / 8
PCT/NZ99/00026
Spray dried UF, DF retentate powder from milk preteated
at pH 7.5 and 85° C, cooled, adjusted to pH 6.8 with
sulfuric acid. Example 7A.
Figure 5
SUBSTITUTE SHEET (RULE 26)
WO 00/51440
6 / 8
PCT/NZ99/00026
Spray dried UF, DF retentate powder from milk preteated
at pH 9.5 and 65° C, cooled, adjusted to pH 6.8 with
sulfuric acid. Example 7B.
Figure 6
SUBSTITUTE SHEET (RULE 26)
WO 00/51440
7 / 8
PCT/NZ99/00026
Spray dried UF, DF retentate from milk without preteated
or pH adjustments. Example 10.
Figure 7
SUBSTITUTE SHEET (RULE 26)
WO 00/51440
8 / 8
PCT/NZ99/00026
Spray dried skim milk.
Figure 8
SUBSTITUTE SHEET (RULE 26)
INTERNATIONAL SEARCH REPORT
International application No.
PCT/NZ 99/00026
A-
CLASSIFICATION OF SUBJECT MATTER
Int Cl 6: A23C 1/00; 9/142; 9/18. A23J 1/20;
According to International Patent Classification (IPC) or to both national classification and IPC
B.
FIELDS SEARCHED
Minimum documentation searched (classification system followed by classification symbols)
AS ABOVE
Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched
SEE BELOW
Electronic data base consulted during the international search (name of data base and, where practicable, search terms used)
WAPT, CA, FSTA: (i) milk, protein, concentrate, pH, membrane filtration, dialysis, ultrafiltration, diafiltration
(ii) milk, calcium, alkaline, pH (7 or 8 or 9 or 10)
(iii) -
DOCUMENTS CONSIDERED TO BE RELEVANT
Category*
Citation of document, with indication, where appropriate, of the relevant passages
Relevant to claim No.
X
Y
Y
JP 4-360645. Meiji Milk Production Company. 14.12.92
US 4 3760 72. New Zealand Milk Products. 8.3.83
Varnam and Sutherland. Milk and Milk Products. 1994. Chapman and Hall,
London. Chapter 4, Dairy Protein Products, pp 175 -176
27-30
All
All
| | Further documents are listed in the
continuation of Box C
| [ See patent family annex
"A"
n E tt
"L"
"O"
«p«i
Special categories of cited documents:
document defining the general state of the art -which is
not considered to be of particular relevance
earlier application or patent but published on or after
the international filing date
document which may throw doubts on priority claim(s)
or which is cited to establish the publication date of
another citation or other special reason (as specified)
document referring to an oral disclosure, use,
exhibition or other means
document published prior to the international filing
date but later than the priority date claimed
"T" later document published after the international filing date or
priority date and not in conflict with the application but cited to
understand the principle or theory underlying the invention
"X" document of particular relevance; the claimed invention cannot
be considered novel or cannot be considered to involve an
inventive step when the document is taken alone
" Y M document of particular relevance; the claimed invention cannot
be considered to involve an inventive step when the document is
combined with one or more other such documents, such
combination being obvious to a person skilled in the art
document member of the same patent family
Date of the actual completion of the international search
Date of mailing of the international search report
0 8 JUL 1999
Name and mailing address of the ISA/AU
AUSTRALIAN PATENT OFFICE
PO BOX 200
WODEN ACT 2606
AUSTRALIA
Facsimile No.: (02) 6285 3929
Authorized officer
GILLIAN ALLEN
Telephone No.: (02) 6283 2266
Form PCT/ISA/210 (second sheet) (July 1998)
INTERNATIONAL SEARCH REPORT
International application No.
PCT/NZ 99/00026
C (Continuation)
DOCUMENTS CONSIDERED TO BE RELEVANT
Category"'
Y
A
Citation of document, with indication, where appropriate, of the relevant passages
VanDijk. Neth. Milk Dairy J. 1992. 46:101-103.
Singh and Fox. J Dairy research. 1987. 54:523-534
Relevant to
claim No.
27-36
All
Form PCT/ISA/210 (continuation of Box C) (July 1998)
INTERNATIONAL SEARCH REPORT
International application No.
PCT/NZ 99/00026
Box 1
Observations where certain claims were found unsearchable (Continuation of item 1 of first sheet)
This international search report has not been established in respect of certain claims under Article 17(2)(a) for the following
reasons:
□
Claims Nos.:
because they relate to subject matter not required to be searched by this Authority, namely:
2.
□
Claims Nos.:
because they relate to parts of the international application that do not comply with the prescribed requirements
to such an extent that no meaningful international search can be carried out, specifically:
□
Claims Nos.:
because they are dependent claims and are not drafted in accordance with the second and third sentences of Rule
6.4(a)
Box II
Observations where unity of invention is lacking (Continuation of item 2 of first sheet)
This International Searching Authority found multiple inventions in this international application, as follows:
See attached continuation of Box II
□
□
As all required additional search fees were timely paid by the applicant, this international search report covers
all searchable claims
As all searchable claims could be searched without effort justifying an additional fee, this Authority did not
invite payment of any additional fee.
As only some of the required additional search fees were timely paid by the applicant, this international search
report covers only those claims for which fees were paid, specifically claims Nos. :
4.
No required additional search fees were timely paid by the applicant. Consequently, this international search
report is restricted to the invention first mentioned in the claims; it is covered by claims Nos.1-26:
Remark on Protest
| [ The additional search fees were accompanied by the applicant's protest.
P"[ No protest accompanied the payment of additional search fees.
Form PCT/ISA/210 (continuation of first sheet(l)) (July 1998)
INTERNATIONAL SEARCH REPORT
International application No.
PCT/NZ 99/00026
Box n (cont'd)
Invention 1 defined by claims 1-26 is to a method of preparing a reduced lactose milk concentrate, characterised by the
following steps
a) pH adjustment to 7.5-10
b) heating to 60-90°C
d) cooling to 5-55 °C
e) membrane filtration
Invention 2 defined by claims 27-34 is to a method of preparing, from milk, a composition with an increased calcium to
protein ration, characterised by the following steps
a) pH adjustment to 7.5-10 with a calcium containing alkalising agent
b) adding a neutralising agent to return pH to 7-7.5 .
Invention 3 defined by claim 35 is to a method preparing a milk concentrate which has specific viscosity characteristics,
characterised by the following steps
adjusting pH to 9-10
heating to 80-100 °C
cooling to 5-55 °C
adjusting pH to 7.5-5.5
drying
The problem to be solved by each invention is different, and the three inventions are to three different treatments of milk
which have no common technical feature that represents the advance over the prior art of all three inventions.
a)
b)
c)
d)
e)
Form PCT/ISA/210 (extra sheetXJuly 1998)
INTERNATIONAL SEARCH REPORT
Information on patent family members
This Annex lists the known "A" publication level patent family members relating to the patent documents cited
in the above-mentioned international search report. The Australian Patent Office is in no way liable for these
particulars which are merely given for the purpose of information.
Patent Document Cited in Search
Report
Patent Family Member
1. US 4 376 072
AU 7725/54
EP 64509
WO 820164
2. JP 4-360645
NONE
END OF ANNEX
International application No.
PCT/NZ 99/00026
Form PCT/ISA/210 (citation family annex) (July 1998)
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